This invention relates generally to engines, and more particularly to common rail fuel injection systems that use a common electrical actuator(s) to control multiple fuel injectors.
Common rail fuel injection systems are becoming more widespread for use with diesel engines. One example of such a fuel injection system is shown and described in U.S. Pat. No. 5,133,645, which issued to Crowley et al. on Jul. 28, 1992. Crowley et al. includes an electronic control module and an electronic distribution unit which control a plurality of high pressure fuel supply pumps and fuel injectors. As with other traditional common rail fuel injection systems, each of the fuel injectors included in the Crowley et al. fuel injection system includes its own individual electrical actuator. In this and other common rail fuel injection systems, the individual electrical actuators must cooperate to ensure that the proper amount of fuel is injected from each injector at the proper time. While the Crowley fuel injection system has performed adequately, there is room for improvement. For instance, if the number of electrical actuators, or solenoids, could be reduced, this could benefit the fuel infection system in a number of ways. First, because the number of parts has been reduced, there are less parts that can fail during system operation and hinder system performance. Additionally, injector performance variability might be reduced. Any reduction in the number of moving and/or electrical components should improve system robustness.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention, an engine comprises an engine housing, a high pressure fuel rail and a low pressure fuel drain. A plurality of fuel injectors included in a fuel injection system are positioned within the engine housing and are fluidly connected to the fuel rail. Each of the plurality of fuel injectors includes an injector body that defines a nozzle outlet and a nozzle supply passage. Also included in each of the plurality of fuel injectors is a needle valve member that is movably positioned in the injector body adjacent the nozzle outlet. A fluid switch that has a plurality of positions is also included in the engine. An electronically controlled valve is positioned between the fluid switch and the fuel drain. A different one of the plurality of fuel injectors is fluidly connected to the electronically controlled valve at each of the plurality of positions of the fluid switch.
In another aspect of the present invention, a fuel injection system comprises a high pressure fuel rail and a low pressure fuel drain. A plurality of fuel injectors is fluidly connected to the high pressure fuel rail. Each of the plurality of fuel injectors includes an injector body that defines a nozzle outlet, at least one high pressure fluid inlet, at least one low pressure fluid drain, at least one fluid passageway and a nozzle supply passage, and includes a direct control needle valve member movably positioned in the injector body adjacent the nozzle outlet. The direct control needle valve member includes a closing hydraulic surface that is exposed to fluid pressure in a needle control chamber. A first of the at least one fluid passageways is fluidly connected to the high pressure fuel rail. A second of the at least one fluid passageways is fluidly connected to the low pressure fuel drain. A fluid switch is included in the fuel injection system that has a plurality of positions. An electronically controlled valve is positioned remote from the plurality of fuel injectors fluidly between the fluid switch and the fuel drain. A different one of the plurality of fuel injectors is fluidly connected to the electronically controlled valve at each of the plurality of positions.
In yet another aspect of the present Invention, a method of fuel injection comprises providing an engine that includes a fuel injection system. The fuel injection system has a high pressure fuel rail, a low pressure fuel drain, a plurality of fuel injectors that each include an injector body that defines a needle control chamber, a fluid switch having a plurality of positions and an electronically controlled valve. The electronically controlled valve is positioned remote from the plurality of fuel injectors between the fluid switch and the low pressure fuel drain. One of the plurality of fuel injectors is enabled to be fluidly connected to the electronically controlled valve, in part by moving the fluid switch to a first position. Next, the electronically controlled valve is moved to an open position to open the needle control chamber of the one fuel injector to fluid communication with the low pressure fuel drain. An amount of fuel is then injected from the one fuel injector. The electronically controlled valve is next moved to a closed position to block the needle control chamber of the one fuel injector from fluid communication with the low pressure fuel drain. The one fuel injector is then prevented from being open to the electronically controlled valve and an other of the plurality of fuel injectors is enabled to be fluidly connected to the electronically controlled valve, in part by moving the fluid switch to a second position.